The present invention relates to an arrangement for separation of coarse matter and/or bulky solids in rainwater relief structures. The present invention relates particularly also to a rain basin for sewage treatment plants featuring an overflow for treated water.
Arrangements of this type are known--notably in drainage systems in conjunction with circular rainwater relief structures, for example in OS 41 25 419 and DE-OS 41 39 572, and, by and large, have proved themselves. The intended purpose of rain basins and rainwater relief structures such as retention basins, overflow basins, channel checks and overflows consists in damping the rainwater influx into a receiving body of water and extensively retaining the coarse matter pollutants floating in and on it. The pollutants are then passed to a treatment plant, notably the sedimentation plant.
A rain basin for sewage systems with an overflow for clarified water having an overflow arranged at the basin rim formed by a clear water drain with an overflow weir and a clear water line and where at the transition from the basin to the clear water drain there is an interceptor provided for retention of the pollutants is known, e.g., from DE-PS 24 58 157 and DE-PS 26 13 578. To retain suspended and floating coarse matter, an immersed wall is coordinated here with the overflow. While the water or waste water flowing via the clear water drain to a receiving body of water or similar is thereby relatively dependably rid of the coarse matter carried by the influx in the rain basin, it remains to be stated as regards the coarse matter rising between the immersed wall and the clear water drain that these will proceed into the clear water drain and, as the case may be, clog the clear water line.
The present invention relates quite generally to a coarse matter separation for any kind and any application of separating structures for the protection of bodies of water, that is, for storm sewers just the same as for combined sewers, but also for any conceivable random aggregation and combination of structures. The question of the shape of these structures is just as irrelevant as is that of whether the structure is employed within a network of sewers, in conjunction with rainwater relief or as a rain basin with a sedimentary or basin overflow. The basic concern simply is to separate a flow of matter in two partial flows whereof one is a drainage adjusted to a prescribed limit value, while the second partial flow represents the excess that needs to be, or is, separated for specific treatment.
The screen systems known in conjunction with the aforementioned rainstorm basins have proved themselves as regards their operating principle--but exactly with circular tanks it has been demonstrated that the spiral flow, which ensures a good removal of coarse matter via the bottom drain line, may be excessively impaired nonetheless. Moreover, it has been noted that the flow from the tank and through the screen setup is associated with a relatively strong buoyancy which, possibly, is capable of entraining also coarser pollutants.
The problem underlying the present invention, more generally, consists in providing an arrangement of the categorical type where the flow in the rainwater basin remains entirely unaffected.